Is time a fiction?

Newton introduced time as a mathematical quantity t against which we can measure the motion of things. I similarly treat time as a parameter with which to measure the change of a system, e.g., the motion of a spaceship, or the change in the weather. In fact, our notions of "change" are almost inseparable from "change as time goes by". But time may not be something objective "out there" in the real world... It may simply be a convenient tool for measurements and theories.

I think I perceive change in time, but is my internal clock the same ar yours? or someone's on a planet in a far away galaxy?

Is time a fiction? Or is it as real as, say, the three-dimensional space inside the room in which I sit? Or is space a fiction too? For that matter, may as well throw out "I".